The Arizona Republican's announcement gives a boost to GOP leaders hoping to push the measure through the chamber this week.

McCain says the tax legislation is "far from perfect." But he says the measure would spur the economy and ease the tax burden for middle class families.

“For too long, hardworking people in Arizona and around the country have not seen a raise in their paychecks,” McCain said. “This bill would directly benefit all Americans, allowing them to keep a higher percentage of what they earn.”

McCain was among three Republicans who helped derail the party's effort to repeal President Barack Obama's health care law last summer.